An all or none order (AON) is a type of order in financial markets which must be executed fully at the specified price. An AON does not accept partial filling of the order; it needs full execution.

This type of order can be very helpful to an investor since they can get the number of assets needed at one price. However, it mostly works well with limit orders to limit the price of the assets needed.

How Does it Work?

It’s easier to use an illustration to explain how the AON order works. Trader A wants to purchase 50k ADA at the price of $1.8 each. This is how the order type works;

Trader A puts their market order selecting the amount they want to purchase and the purchase price. Hence, before they click the buy box, they ensure All or None is displayed on their trading screen.
The trade sends their order to the market. On reaching the market, the market price is slightly above their order. But, one individual (trader B) has 40k ADA trading at $1.8. Since this is an all or none order, this trade cannot go through.
Trader C has 50k ADA sold at $1.75. It s a good price for trader A. Hence the buy transaction goes through. Once the number of coins hits 50k, the trade will complete at the $1.8 or lower price.
If the market does not have the required prices and token amount, the trade will continue to get the required price. However, the trader may cancel after realizing that the market is not likely to reach its requirements.